In accordance with standard orthodontic practice, the fixed orthodontic arch wire appliance comprises a plurality of metal brackets which are attached to the anteriors, or other teeth, by bands; and it also comprises a plurality of tubes which are attached to the molars and which act as anchoring means for the appliance. Although such prior art appliances are effective, they are unsightly from an aesthetic standpoint.
In recent years, clear plastic brackets have been used which are adhesively attached to the teeth by a white bonding agent. When such brackets are used in conjunction with white arch wires, the appliance is practically invisible. However, problems have arisen in the use of the prior art plastic brackets in that they have a tendency to break when subjected to turning forces by a rectangular arch wire in the performance of the usual tooth torquing and tipping procedures. Moreover, the plastic brackets, due to their lack of rigidity, do not translate the angulations accurately to the teeth. Moreover, the metal arch wire does not slide freely through the slots provided in the plastic brackets, thus slowing orthodontic movement. In addition, forces of occlusion tend to fracture the plastic brackets.
The hybrid appliance of the present invention incorporates all the features of the prior art plastic bracket in that it may be firmly bonded to the teeth by an adhesive, and in that it is practically invisible. Moreover, the metal insert provided in the appliance of the invention makes it capable of being subjected to strong torquing and tipping forces by the arch wire without any tendency to break.
The metal portion of the hybrid appliance of the invention, being rigid, translates angulations of the arch wire to the tooth being treated accurately without the elastic flow of plastic. The metal arch wire has less frictional drag in the metal slots provided in the hybrid appliance, so that orthodontic movement is faster. The hybrid appliance also has the advantage in that the forces of occlusion will not break the appliance because of the metal reinforcement. Thus, the laminated hybrid appliance of the present invention has all the advantages of plastic and metal because the metal is provided with a white coating to make the applicance practically invisible. The coating is protected from wearing off the metal by the plastic housing in which the metal is embedded.